CoCoRaHS

CoCoRaHS is a unique, non-profit, community-based network of volunteers of all ages and backgrounds working together to measure and map precipitation.

Thursday, April 3, 2014

40th Anniversary of the April 3-4, 1974 Super Outbreak

In a little under 18 hours from April 3 to the early morning hours of April 4, 1974 the central and eastern U.S. experienced a historic damaging and deadly tornado outbreak. 148 tornadoes left a path of destruction across 13 states from eastern Missouri through Illinois, Indiana, Kentucky, Ohio, Alabama, and North Carolina, South Carolina, Michigan, Mississippi, and West Virginia.The storms were most numerous and the damage concentrated in Alabama, Georgia, Tennessee, Kentucky, Indiana, and Ohio.The storms resulted in 330 tornado-related deaths, 5,484 injuries, and $600 million in damages. The outbreak produced an astounding seven F5 tornadoes and 23 F4 tornadoes. The 1974 Super Outbreak occurred in a time before Doppler radar and well before the Internet and it's ability to rapidly and widely disseminate information. NOAA Weather radio was in its early stages of deployment.

On April 3, 1974 the early morning weather map depicted a strong low pressure system in central Kansas with a cold front trailing south into eastern Texas. and a warm front extending east from the cold front through Arkansas Tennessee, and North Carolina. South of the front warm, humid Gulf air was in place. A line of early morning thunderstorms were moving through eastern Missouri and western Illinois. Northwest of the low pressure center snow was falling in western Kansas, eastern Colorado, and southern Nebraska.

Portion of surface weather map for 7:00 a.m. CDT, April 3, 1974

Forecasters at the National Severe Storms Forecast Center (now the Storm Prediction Center) saw the potential for severe weather the day before and had notified Weather Services Offices to be ready. However, the extent and intensity of the severe weather was still uncertain. By the morning of April 3 the potential for severe weather was coming into better focus. The first Severe Thunderstorm Watch was issued at 8:27 a.m. CDT for the Ohio Valley, and over the next 19 hours 28 severe weather watches were issued covering almost the entire area from the Gulf of Mexico to the Canadian border and from the Mississippi River to the East Coast.

Map of the tornado tracks for April 3-4, 1974
prepared by Dr. Ted Fujita

It was early afternoon when the severe weather development became explosive. A severe thunderstorm hit St. Louis at about 1:05 pm CDT. This storm, which had high winds and 2.75 in hail (baseball-size) caused 25 injuries and $45 million in damage, a record hail loss at the time. A lot of the hail hit in the part of the city were the were a number of car dealerships, and cars in the lots were decimated by the hail.

The first tornado of the outbreak touched down in Morris, IL (Grundy County). It was a weak (F0) tornado that was on the ground for only a tenth of a mile. An hour later two more tornadoes touched down in central Illinois, quickly followed by more tornadoes in Illinois and Indiana. Storms spawned tornadoes throughout the afternoon and evening at a rapid pace. At one point a total of 15 tornadoes were on the ground at the same time, and meteorologists in Indiana placed the entire state under a tornado warning. This was the first and only time in U.S. history that an entire state was under a tornado warning.

The F5 tornado as hit hit downtown Xenia, OH.Photo by Kitty Marchant

The deadliest tornado to occur was the F5 tornado that destroyed much of Xenia, Ohio. 32 people were killed and 1,150 were injured. Almost half the buildings in Xenia were damaged or destroyed, and damages were in excess of $100 million (1974 dollars) About the time the Xenia tornado developed near Bellbrook, OH, another tornado touched down in Breckinridge County, KY and quickly intensified to produce F5 damage as it plowed through Brandenburg KY. As the afternoon wore on and the atmosphere became more unstable thunderstorm supercells developed eastward through the Southeast U.S.

Depiction of the upper level conditions (left) and surface conditions (righ)t at 7:00 p.m. CDT on April 3, 1974

There is no way to thoroughly write about all that occurred on the 18 hour period in April 1974 in a blog post. It was a much-researched and documented event. You can easily spend many hours reading through the huge amount of information available on the 1974 Super Outbreak. The Super Outbreak led to significant changes in warning procedures for severe weather. Many communities that did not have outdoor warning sirens did so in the aftermath of the Super Outbreak. NOAA's Weather Radio network rapidly expanded in the wake of the Super Outbreak so that warnings could be quickly disseminated. It also helped spur the National Weather Service modernization program.

This short documentary on the Super Outbreak provides an overview of just what forecasters and the public were up against that day. This shows actual footage of tornadoes as they struck Xenia, Cincinnati, and Louisville, causing massive damage and numerous deaths. Includes discussion of advance tornado preparation and emergency coordination. Courtesy of the National Archives.

Here are some sources for further reading. Many of these include numerous photographs, news accounts, and first-hand accounts of the events of that day. Several of the NWS pages contain links to other data and information about the Super Outbreak